c) After doctrinal differences with Unitarians who refused them use of Unitarin Church premises, the three founded Brahma Sabha in 1828 and acquired their own premises in 1830 at Chitpur Road which is now known as Adi Brahmo Samaj.

The historical points are essentially true, but there is no dynastic succession in the Adi Brahmo Samaj. There is no "head" of Adi Brahmo Samaj and membership / leadership is not limited to "Tagores" or their descendants.

Your question is academic; Adi Brahmo Samaj by itself is no longer directly active except to extent of providing intellectual, theological and spiritual leadership to associated movements like Adi Dharma and even more radical indigenous peoples movements.